Within the electronics industry, vigorous development has focused on multi-functional and high-performance capabilities of electronic products. To meet the integration and miniaturization packaging requirements of semiconductor package structures, circuit board designs for carrying active and passive components and wirings have evolved from single-layer to multi-layer board designs. With a multi-layer board, an area of wire routing can be expanded in a limited space on the circuit board by employing an interlayer connection technique, which also complies with the requirements of high-density integrated circuits.
This Discussion of the Background section is provided for background information only. The statements in this Discussion of the Background are not an admission that the subject matter disclosed in this section constitutes prior art to the present disclosure, and no part of this Discussion of the Background section may be used as an admission that any part of this application, including this Discussion of the Background section, constitutes prior art to the present disclosure.